IBM Informix Backup and Restore Guide

Transcription

1 Informix Product Family Informix Version IBM Informix Backup and Restore Guide SC

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3 Informix Product Family Informix Version IBM Informix Backup and Restore Guide SC

4 Note Before using this information and the product it supports, read the information in Notices on page E-1. This edition replaces SC This document contains proprietary information of IBM. It is proided under a license agreement and is protected by copyright law. The information contained in this publication does not include any product warranties, and any statements proided in this manual should not be interpreted as such. When you send information to IBM, you grant IBM a nonexclusie right to use or distribute the information in any way it beliees appropriate without incurring any obligation to you. Copyright IBM Corporation 2006, US Goernment Users Restricted Rights Use, duplication or disclosure restricted by GSA ADP Schedule Contract with IBM Corp.

5 Contents Introduction xi In this introduction xi About this publication xi Types of users xi Software dependencies xi Assumptions about your locale xii Demonstration database xii What's new in the Backup and Restore Guide, Version xii Example code conentions xiii Additional documentation xi Compliance with industry standards xi Syntax diagrams xi How to read a command-line syntax diagram x Keywords and punctuation xii Identifiers and names xii How to proide documentation feedback xii Part 1. Oeriew of backup and restore Chapter 1. Backup and restore concepts Recoery system Backup systems Logical-log backup Restore systems Comparing ON-Bar and ontape Chapter 2. Plan for backup and restore Plan a recoery strategy Types of data loss Determine failure seerity Data use determines your backup schedule Schedule backups Security requirements for label-based access control Plan a backup system for a production database serer Ealuate hardware and memory resources Ealuate backup and restore time Ealuate logging and transaction actiity Compress row data Transform data with external programs Part 2. ON-Bar backup and restore system Chapter 3. Oeriew of the ON-Bar backup and restore system Where to find information about tasks for ON-Bar, ISM, and TSM ON-Bar components for Informix ON-Bar utilities IBM Informix Storage Manager IBM Tioli Storage Manager Third-party storage managers XBSA interface ON-Bar tables ON-Bar boot files ON-Bar actiity log Transform data with external filter programs Copyright IBM Corp. 2006, 2011 iii

6 Chapter 4. Configure the storage manager and ON-Bar Configure a storage manager Configuring a third-party storage manager Configure ISM Configure TSM Update the sm_ersions file Updating the storage-manager definition in sm_ersions Validate your storage manager Configure ON-Bar The bargroup group (UNIX) Your customized onbar script is saed on new installations Set ISM enironment ariables and ONCONFIG parameters Set the IBM Informix Interface for TSM enironment ariables Specify the location of the XBSA Library Specify ON-Bar configuration parameters ON-Bar configuration parameters on Informix Verify the configuration Choose storage managers and storage deices Features that ISM supports Features that ISM does not support Features that TSM supports Storage deice requirements Chapter 5. Back up with ON-Bar Summary of ON-Bar tasks Prepare for a backup Data ON-Bar backs up Administratie files to back up Install and configure a storage manager Whole-system backup Parallel backup Standard backup Incremental backup Physical backup Choose a backup leel Collect information about your system before a backup Back up storage spaces and logical logs Backup syntax Back up after changing the physical schema Use ISM during a backup Use ISA to back up and erify ON-Bar backup examples Back up table types View recent ON-Bar actiity Viewing a list of registered backups Back up logical logs Back up logical logs on Informix Monitor logical-log backups Salage logical-log files ON-Bar backup processes Backup sequence on Informix Chapter 6. Restore data with ON-Bar ON-Bar restore types Warm restore Cold restore Mixed restore Parallel restore Point-in-time restore Imported restore i IBM Informix Backup and Restore Guide

7 Rename chunks restore Restartable restore Continuous log restore Pre-recoery checklist Monitor restores Ensure that storage deices are aailable Restore sae sets with ISM Perform a complete restore Perform a physical-only or logical-only restore Use ISA to restore data Examples of ON-Bar restore commands Configuring continuous log restore by using ON-Bar Rename chunks during a restore Key considerations New-chunk requirements Syntax Examples of renaming chunks during a restore Transfer data with the imported restore Setting up an imported restore Importing a restore Initializing High-aailability Data Replication with ON-Bar Restore nonlogging databases and tables Restore table types Restore tables with large objects Use restartable restore to recoer data Restartable restore example Restart a restore Resole a failed restore ON-Bar restore processes Warm-restore sequence Cold-restore sequence Chapter 7. External backup and restore External backup and restore oeriew Block before backing up Rules for an external backup Prepare for an external backup Performing an external backup when chunks are not mirrored RS secondary serer external backup Performing an external backup of an RS secondary serer Data restored in an external restore Rename chunks External restore commands Rules for an external restore Performing an external restore Initializing HDR with an external backup and restore Chapter 8. Customize and maintain ON-Bar Customize ON-Bar and storage-manager commands Print the backup boot files Migrate backed-up logical logs to tape Expire and synchronize the backup catalogs Choose an expiration policy The onsmsync utility Monitor the performance of ON-Bar and the storage managers Set ON-Bar performance statistics leels View ON-Bar backup and restore performance statistics Chapter 9. ON-Bar configuration parameters Configuration parameters for archecker in AC_CONFIG Contents

8 AC_CONFIG file enironment ariable AC_MSGPATH parameter AC_STORAGE parameter AC_TIMEOUT parameter AC_VERBOSE parameter ON-Bar parameters in ONCONFIG ALARMPROGRAM parameter ALRM_ALL_EVENTS parameter BACKUP_FILTER parameter BAR_ACT_LOG parameter BAR_BSALIB_PATH parameter BAR_CKPTSEC_TIMEOUT parameter BAR_DEBUG parameter BAR_DEBUG_LOG parameter BAR_HISTORY parameter BAR_IXBAR_PATH parameter BAR_MAX_BACKUP parameter BAR_NB_XPORT_COUNT parameter BAR_PERFORMANCE parameter BAR_PROGRESS_FREQ parameter BAR_RETRY parameter BAR_SIZE_FACTOR parameter BAR_XFER_BUF_SIZE parameter ISM_DATA_POOL parameter ISM_LOG_POOL parameter LTAPEDEV parameter RESTARTABLE_RESTORE parameter RESTORE_FILTER parameter Files that ON-Bar, ISM, and TSM use Chapter 10. ON-Bar catalog tables The bar_action table The bar_instance table The bar_ixbar table The bar_object table The bar_serer table The bar_syncdeltab table ON-Bar catalog map Chapter 11. ON-Bar messages and return codes About ON-Bar messages Message format Message numbers ON-Bar usage messages ON-Bar return codes Part 3. Backup and restore system for ontape Chapter 12. Configure ontape Configuration parameters for ontape Data transformation filter parameters for ontape Tape and tape deice parameters for ontape Set the tape-deice parameters Specify the tape-block-size parameters Specify the tape-size parameters i IBM Informix Backup and Restore Guide

9 Check and change ontape configuration parameters Change TAPEDEV to /de/null Change LTAPEDEV to /de/null Verify that the tape deice can read the specified block size Change ontape parameters Chapter 13. Back up with ontape Summary of ontape tasks Start ontape Exit codes for ontape Change database logging status Create a backup Backup leels Back up after changing the physical schema Prepare for a backup Perform a backup When the logical-log files fill during a backup When a backup terminates prematurely Monitor backup history by using oncheck Back up logical-log files with ontape Before you back up the logical-log files When to back up logical-log files Start an automatic logical-log backup Starting a continuous logical-log file backup End a continuous logical-log backup Deices that logical-log backups must use Chapter 14. Restore with ontape Types of physical restore Full-system restore Restores of dbspaces, blobspaces, and sbspaces Cold, warm, or mixed restores Cold restores Warm restores Mixed restores Perform a restore Restore the whole system Gather the appropriate tapes Decide on a complete cold or a mixed restore Verify your database serer configuration Perform a cold restore Restore selected storage spaces Restore raw tables Configuring continuous log restore with ontape Rename chunks during a restore Validation sequence for renaming chunks New chunk requirements Rename chunks with command-line options Rename chunks with a file Rename chunks while specifying other options Rename a chunk to a nonexistent deice Restore from standard input Restore data to a remote serer Simultaneous backup and restore by using standard I/O Chapter 15. Perform an external backup and restore Recoer data by using an external backup and restore Data that is backed up in an external backup Rules for an external backup Performing an external backup Contents ii

10 Prepare for an external backup Block and unblock Informix Track an external backup Data that is restored in an external restore Use external restore commands Rules for an external restore Rename chunks Performing a cold external restore Initializing HDR with an external backup and restore Part 4. Verify and restore backups with archecker Chapter 16. Verify backups The archecker configuration file Verify backups by using archecker in integrated mode Syntax for archecker by using integrated mode Estimate the amount of temporary space for archecker Verify backups Interpret erification messages Verification failures Fixing backup erification problems Verification process with archecker Verifying backups by using archecker in stand-alone mode Syntax for archecker Chapter 17. Perform table-leel restores by using the archecker utility Oeriew of archecker Configuration file Schema command file Table-leel restore and locales Data restore with archecker Physical restore Logical restore Syntax for archecker table-leel restores Manually control a logical restore Performing a restore with multiple storage managers Perform a parallel restore Restore transformed data When to delete restore files The archecker schema reference The CREATE TABLE statement The CREATE EXTERNAL TABLE statement The DATABASE statement The INSERT statement The RESTORE statement The SET statement Schema command file examples Chapter 18. The archecker configuration parameter reference Configuration parameters AC_DEBUG parameter AC_IXBAR parameter AC_LTAPEBLOCK parameter AC_LTAPEDEV parameter AC_MSGPATH parameter AC_RESTORE_FILTER parameter AC_SCHEMA parameter AC_STORAGE parameter AC_TAPEBLOCK parameter AC_TAPEDEV parameter iii IBM Informix Backup and Restore Guide

11 AC_VERBOSE parameter Part 5. Appendixes Appendix A. Troubleshooting A-1 Corrupt page during an archie A-1 Log backup already running A-1 No serer connection during a restore A-2 Drop a database before a restore A-2 No dbspaces or blobspaces during a backup or restore A-2 Restore blobspace BLOBs A-3 Changing the system time on the backup system A-3 Appendix B. Migrate data, serers, and tools B-1 Use data-migration tools for recoery B-1 Preparing for a database serer or storage-manager upgrade B-1 Upgrade your storage manager B-1 Change storage-manager endors B-1 Migrating from ontape to ON-Bar B-2 Migrate priate ON-Bar scripts B-2 Appendix C. GLS support C-1 Use GLS with ON-Bar C-1 Identifiers that support non-ascii characters C-1 Identifiers that require 7-bit ASCII characters C-1 Locale of ON-Bar messages C-1 Use the GL_DATETIME enironment ariable with ON-Bar C-2 Point-in-time restore example C-2 Use GLS with ontape C-2 Appendix D. Accessibility D-1 Accessibility features for IBM Informix products D-1 Accessibility features D-1 Keyboard naigation D-1 Related accessibility information D-1 IBM and accessibility D-1 Dotted decimal syntax diagrams D-1 Notices E-1 Trademarks E-3 Index X-1 Contents ix

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13 Introduction In this introduction About this publication This introduction proides an oeriew of the information in this manual and describes the conentions it uses. These topics describe how to use the IBM Informix ON-Bar and ontape utilities to back up and restore database serer data. These utilities enable you to recoer your databases after data is lost or becomes corrupt due to hardware or software failure or accident. ON-Bar requires IBM Informix Storage Manager, Version 2.2, IBM Tioli Storage Manager, or a third-party storage manager to manage the storage deices. Important: The ontape utility does not require a storage manager and works on IBM Informix only. Types of users These topics were written for the following users: Database administrators System administrators Backup operators Technical support personnel These topics are written with the assumption that you hae the following background: Some experience with storage managers, which are applications that manage the storage deices and media that contain backups A working knowledge of your computer, your operating system, and the utilities that your operating system proides Some experience working with relational databases or exposure to database concepts Some experience with database serer administration, operating-system administration, or network administration You can access the Informix information centers, as well as other technical information such as technotes, white papers, and IBMRedbooks publications online at Software dependencies This publication is written with the assumption that you are using IBM Informix Version as your database serer. Copyright IBM Corp. 2006, 2011 xi

14 Assumptions about your locale IBM Informix products can support many languages, cultures, and code sets. All the information related to character set, collation, and representation of numeric data, currency, date, and time is brought together in a single enironment, called a Global Language Support (GLS) locale. The examples in this manual are written with the assumption that you are using the default locale, en_us This locale supports U.S. English format conentions for date, time, and currency. In addition, this locale supports the ISO code set, which includes the ASCII code set plus many 8-bit characters such as "è", "é", and "ñ". If you plan to use nondefault characters in your data or your SQL identifiers, or if you want to conform to the nondefault collation rules of character data, you need to specify the appropriate nondefault locale. For instructions on how to specify a nondefault locale, additional syntax, and other considerations related to GLS locales, see the IBM Informix GLS User's Guide. Demonstration database The DB-Access utility, which is proided with the database serer products, includes one or more of the following demonstration databases: The stores_demo database illustrates a relational schema with information about a fictitious wholesale sporting-goods distributor. Many examples in IBM Informix manuals are based on the stores_demo database. The superstores_demo database illustrates an object-relational schema. The superstores_demo database contains examples of extended data types, type and table inheritance, and user-defined routines. For information about how to create and populate the demonstration databases, see the IBM Informix DB-Access User's Guide. For descriptions of the databases and their contents, see the IBM Informix Guide to SQL: Reference. The scripts that you use to install the demonstration databases reside in the $INFORMIXDIR/bin directory on UNIX and in the %INFORMIXDIR%\bin directory on Windows. What's new in the Backup and Restore Guide, Version This publication includes information about new features and changes in existing functionality. The following changes and enhancements are releant to this publication. For a comprehensie list of all new features for this release, see the IBM Informix Getting Started Guide. xii IBM Informix Backup and Restore Guide

15 Table 1. What's new in the Backup and Restore Guide for Version xC8 Oeriew Reference New editions and product names IBM Informix Dynamic Serer editions were withdrawn and new Informix editions are aailable. Some products were also renamed. The publications in the Informix library pertain to the following products: IBM Informix database serer, formerly known as IBM Informix Dynamic Serer (IDS) IBM OpenAdmin Tool (OAT) for Informix, formerly known as OpenAdmin Tool for Informix Dynamic Serer (IDS) IBM Informix SQL Warehousing Tool, formerly known as Informix Warehouse Feature For more information about the Informix product family, go to Table 2. What's new in the Backup and Restore Guide for Version xC6 Oeriew Reference External Backups on RS Secondary Serers RS secondary serer external backup on page 7-4 To reduce the processing load on the primary serer in a high-aailability cluster you can create an external backup on an RS secondary serer instead of on the primary serer. The RS secondary serer must not contain any non-logged objects. You can restore the backup on any serer in the cluster. IBM Informix Administrator's Reference Table 3. What's new in the Backup and Restore Guide for Version xC4 Oeriew Reference Information about the archecker utility has been Part 4, Verify and restore backups with archecker consolidated Example code conentions Examples of SQL code occur throughout this publication. Except as noted, the code is not specific to any single IBM Informix application deelopment tool. If only SQL statements are listed in the example, they are not delimited by semicolons. For instance, you might see the code in the following example: CONNECT TO stores_demo... DELETE FROM customer WHERE customer_num = COMMIT WORK DISCONNECT CURRENT To use this SQL code for a specific product, you must apply the syntax rules for that product. For example, if you are using an SQL API, you must use EXEC SQL at the start of each statement and a semicolon (or other appropriate delimiter) at the end of the statement. If you are using DB Access, you must delimit multiple statements with semicolons. Introduction xiii

16 Additional documentation Tip: Ellipsis points in a code example indicate that more code would be added in a full application, but it is not necessary to show it to describe the concept being discussed. For detailed directions on using SQL statements for a particular application deelopment tool or SQL API, see the documentation for your product. Documentation about this release of IBM Informix products is aailable in arious formats. You can access or install the product documentation from the Quick Start CD that is shipped with Informix products. To get the most current information, see the Informix information centers at ibm.com. You can access the information centers and other Informix technical information such as technotes, white papers, and IBM Redbooks publications online at Compliance with industry standards Syntax diagrams IBM Informix products are compliant with arious standards. IBM Informix SQL-based products are fully compliant with SQL-92 Entry Leel (published as ANSI X ), which is identical to ISO 9075:1992. In addition, many features of IBM Informix database serers comply with the SQL-92 Intermediate and Full Leel and X/Open SQL Common Applications Enironment (CAE) standards. The IBM Informix Geodetic DataBlade Module supports a subset of the data types from the Spatial Data Transfer Standard (SDTS) Federal Information Processing Standard 173, as referenced by the document Content Standard for Geospatial Metadata, Federal Geographic Data Committee, June 8, 1994 (FGDC Metadata Standard). IBM Informix Dynamic Serer (IDS) Enterprise Edition, Version is certified under the Common Criteria. For more information, see Common Criteria Certification: Requirements for IBM Informix Dynamic Serer, which is aailable at &FNC=SRX&PBL=SC Syntax diagrams use special components to describe the syntax for statements and commands. Table 4. Syntax Diagram Components Component represented in PDF Component represented in HTML Meaning >> Statement begins > Statement continues on next line. > Statement continues from preious line. xi IBM Informix Backup and Restore Guide

17 Table 4. Syntax Diagram Components (continued) Component represented in PDF Component represented in HTML Meaning >< Statement ends SELECT LOCAL Required item. Optional item ALL DISTINCT UNIQUE Required item with choice. Only one item must be present FOR UPDATE FOR READ ONLY--.---NEXT PRIOR PREVIOUS , V index_name table_name--- Optional items with choice are shown below the main line, one of which you might specify. The alues below the main line are optional, one of which you might specify. If you do not specify an item, the alue aboe the line is used by default. Optional items. Seeral items are allowed; a comma must precede each repetition. >>- Table Reference ->< Reference to a syntax segment. Table Reference iew table synonym Syntax segment. How to read a command-line syntax diagram Command-line syntax diagrams use similar elements to those of other syntax diagrams. Some of the elements are listed in the table in Syntax Diagrams. Creating a no-conersion job onpladm create job job -p project -n -d deice -D database Introduction x

18 -t table (1) Setting the Run Mode -S serer -T target Notes: 1 See page Z-1 This diagram has a segment named Setting the Run Mode, which according to the diagram footnote is on page Z-1. If this was an actual cross-reference, you would find this segment on the first page of Appendix Z. Instead, this segment is shown in the following segment diagram. Notice that the diagram uses segment start and end components. Setting the run mode: -f d p a l c u n N To see how to construct a command correctly, start at the upper left of the main diagram. Follow the diagram to the right, including the elements that you want. The elements in this diagram are case-sensitie because they illustrate utility syntax. Other types of syntax, such as SQL, are not case-sensitie. The Creating a No-Conersion Job diagram illustrates the following steps: 1. Type onpladm create job and then the name of the job. 2. Optionally, type -p and then the name of the project. 3. Type the following required elements: -n -d and the name of the deice -D and the name of the database -t and the name of the table 4. Optionally, you can choose one or more of the following elements and repeat them an arbitrary number of times: -S and the serer name -T and the target serer name The run mode. To set the run mode, follow the Setting the Run Mode segment diagram to type -f, optionally type d, p, ora, and then optionally type l or u. 5. Follow the diagram to the terminator. xi IBM Informix Backup and Restore Guide

19 Keywords and punctuation Keywords are words resered for statements and all commands except system-leel commands. When a keyword appears in a syntax diagram, it is shown in uppercase letters. When you use a keyword in a command, you can write it in uppercase or lowercase letters, but you must spell the keyword exactly as it appears in the syntax diagram. You must also use any punctuation in your statements and commands exactly as shown in the syntax diagrams. Identifiers and names Variables sere as placeholders for identifiers and names in the syntax diagrams and examples. You can replace a ariable with an arbitrary name, identifier, or literal, depending on the context. Variables are also used to represent complex syntax elements that are expanded in additional syntax diagrams. When a ariable appears in a syntax diagram, an example, or text, it is shown in lowercase italic. The following syntax diagram uses ariables to illustrate the general form of a simple SELECT statement. SELECT column_name FROM table_name When you write a SELECT statement of this form, you replace the ariables column_name and table_name with the name of a specific column and table. How to proide documentation feedback You are encouraged to send your comments about IBM Informix user documentation. Use one of the following methods: Send to docinf@us.ibm.com. In the Informix information center, which is aailable online at open the topic that you want to comment on. Click the feedback link at the bottom of the page, fill out the form, and submit your feedback. Add comments to topics directly in the information center and read comments that were added by other users. Share information about the product documentation, participate in discussions with other users, rate topics, and more! Feedback from all methods is monitored by the team that maintains the user documentation. The feedback methods are resered for reporting errors and omissions in the documentation. For immediate help with a technical problem, contact IBM Technical Support. For instructions, see the IBM Informix Technical Support website at We appreciate your suggestions. Introduction xii

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21 Part 1. Oeriew of backup and restore Copyright IBM Corp. 2006, 2011

22 IBM Informix Backup and Restore Guide

23 Chapter 1. Backup and restore concepts IBM Informix proides two utilities for backing up and restoring database serer data. Both utilities back up and restore storage spaces and logical logs. Howeer, they do support different features and it is important to know the differences. These topics explain basic backup and restore concepts for IBM Informix database serers and compares the ON-Bar and ontape utilities. ON-Bar backs up and restores storage spaces (dbspaces) and logical file, by using a storage manager, whereas ontape does not use a storage manager. Utility Storage manager Where discussed ON-Bar IBM Informix Storage Manager Chapter 3, Oeriew of the (ISM) ON-Bar backup and restore system, on page 3-1 through IBM Tioli Storage Manager (TSM) Chapter 11, ON-Bar messages Third-party storage manager and return codes, on page 11-1 ontape None Chapter 12, Configure ontape, on page 12-1 through Chapter 14, Restore with ontape, on page 14-1 Recoery system Informix does not show errors in standard output (stdout) if an error occurs when you use onbar -b to back up storage spaces or onbar -r to restore storage spaces. Therefore, when you use onbar -b or onbar -r, you must check information in the ON-Bar actiity log (bar_act_log). As ON-Bar backs up and restores data, it writes progress messages, warnings, and error messages to the bar_act.log. A recoery system enables you to back up your database serer data and later restore it if your current data becomes corrupted or inaccessible. The causes of data corruption or loss can range from a program error to a disk failure to a disaster that damages the entire facility. A recoery system enables you to recoer data that you already lost due to such mishaps. Backup systems A backup is a copy of one or more dbspaces (also called storage spaces) and logical logs that the database serer maintains. You can also back up blobspaces and sbspaces. For a description of storage spaces, see your IBM Informix Administrator's Guide. The backup copy is typically written to a secondary storage medium such as disk, magnetic tape, or optical disk. We recommend that you store the media offline and keep a copy off site if possible. Important: Database backups do not replace ordinary operating-system backups, which back up files other than IBM Informix database files. The following figure illustrates the basic concept of a database backup. Copyright IBM Corp. 2006,

24 Database serer data Figure 1-1. A backup of database serer data You do not always hae to back up all the storage spaces. If some tables change daily but others rarely change, it is inefficient to back up the storage spaces that contain the unchanged tables eery time that you back up the database serer. You need to plan your backup schedule carefully to aoid long delays for backing up or restoring data. To proide a more flexible backup enironment, ON-Bar and ontape support the following three backup leels: Leel 0 Leel 1 Leel 2 Backup media Leel 0 backs up all used pages that contain data for the specified storage spaces. You need all these pages to restore the database to the state that it was in at the time that you made the backup. Leel 1 backs up only data that has changed since the last leel-0 backup of the specified storage spaces. All changed table and index pages are backed up, including those pages with deleted data. The data that is copied to the backup reflects the state of the changed data at the time that the leel-1 backup began. Leel 2 backs up only data that has changed since the last leel-1 backup of the specified storage spaces. A leel-2 backup contains a copy of eery table and index page in a storage space that has changed since the last leel-1 backup. Important: If disks and other media are destroyed and need to be replaced, you need at least a leel-0 backup of all storage spaces and releant logical logs to restore data completely on the replacement hardware. For details, see Chapter 5, Back up with ON-Bar, on page 5-1 and Chapter 13, Back up with ontape, on page Logical-log backup A logical-log backup is a copy to disk or tape of all full logical-log files. The logical-log files store a record of database serer actiity that occurs between backups. To free full logical-log files, back them up. The database serer reuses the freed logical-log files for recording new transactions. For a complete description of the logical log, see your IBM Informix Administrator's Guide. Restriction: Een if you do not specify logging for databases or tables, you need to back up the logical logs because they contain administratie information such as 1-2 IBM Informix Backup and Restore Guide

25 checkpoint records and additions and deletions of chunks. When you back up these logical-log files, you can do warm restores een when you do not use logging for any of your databases. Manual and continuous logical-log backups A manual logical-log backup backs up all the full logical-log files and stops at the current logical-log file. If you turn on continuous logical-log backup, the database serer backs up each logical log automatically when it becomes full. If you turn off continuous logical-log backup, the logical-log files continue to fill. If all logical logs are filled, the database serer hangs until the logs are backed up. Log salage When the database serer is offline, you can perform a special logical-log backup, called a log salage. In a log salage, the database serer accesses the log files directly from disk. The log salage backs up any logical logs that hae not yet been backed up and are not corrupted or destroyed. The log salage enables you to recoer all of your data up to the last aailable and uncorrupted logical-log file and the last complete transaction. Sae logical-log backups Perform frequent logical-log backups for the following reasons: To free full logical-log files To minimize data loss if a disk that contains logical logs fails To ensure that restores contain consistent and the latest transactions Sae the logical-log backups from the last two leel-0 backups so that you can use them to complete a restore. If a leel-0 backup is inaccessible or unusable, you can restore data from an older backup, if you hae one. If any of the logical-log backups are also inaccessible or unusable, howeer, you cannot roll forward the transactions from those logical-log files or from any subsequent logical-log files. Important: You lose transactions in logical-log files that are not backed up or salaged. To illustrate, as the following figure shows, suppose you perform a leel-0 backup on Monday at 10 p.m. and then back up the logical logs on Tuesday at midnight. On Wednesday at 11 a.m., you suffer a mishap that destroys your databases. You would be unable to restore the transactions that occurred between midnight on Tuesday and 11 a.m. on Wednesday unless you had continuous logical-log backup setup. If the disks that contain the storage spaces with the logical logs are damaged, the transactions after midnight on Tuesday might be lost. To restore these transactions from the last logical-log backup, try to salage the logical logs before you repair or replace the bad disk and then perform a cold restore. Chapter 1. Backup and restore concepts 1-3

26 Logical-log backup Leel-0 backup Failure Transactions Monday 10 P.M. Tuesday midnight Wednesday 11 A.M. Time Logical-log files Storage-manager logicallog backup media Figure 1-2. Storage space and logical-log backups For more information, see Back up logical logs on page 5-15 and Back up logical-log files with ontape on page Restore systems A restore recreates database serer data from backed-up storage spaces and logical-log files. A restore recreates database serer data that has become inaccessible because of any of the following conditions: You need to replace a failed disk that contains database serer data. A logic error in a program has corrupted a database. You need to moe your database serer data to a new computer. A user accidentally corrupted or destroyed data. To restore data up to the time of the failure, you must hae at least one leel-0 backup of each of your storage spaces from before the failure and the logical-log files that contain all transactions since these backups. Warm, cold, and mixed restores When you restore data, you must decide whether to do so while the database serer is in quiescent, online, or offline. The types of restores are as follows: If you restore noncritical dbspaces while the database serer is online or quiescent, that process is called a warm restore. When IBM Informix is offline, you can perform only a cold restore. A mixed restore is a cold restore of some storage spaces followed by a warm restore of the remaining storage spaces. Warm restore As the following figure shows, a warm restore restores noncritical storage spaces. A warm restore consists of one or more physical restores, a logical-log backup, and a logical restore. 1-4 IBM Informix Backup and Restore Guide

27 Backup media Critical dbspaces Dbspace 1 Dbspace 2 Logical-log backup media Transactions Figure 1-3. Warm restore You cannot perform more than one simultaneous warm restore. Cold restore As the following figure shows, a cold restore salages the logical logs, and restores the critical dbspaces (root dbspace and the dbspaces that contain the physical log and logical-log files), other storage spaces, and the logical logs. Backup media Critical dbspaces Dbspace 1 Dbspace 2 Logical-log backup media Transactions Figure 1-4. Cold restore You can perform a cold restore onto a computer that is not identical to the one on which the backup was performed by giing any chunk a new path name and offset during the restore. When restoring a whole-system backup, it is not necessary to restore the logical logs. A whole-system backup contains a snapshot of the entire instance at the moment the backup was performed, which is logically consistent across all dbspaces. Chapter 1. Backup and restore concepts 1-5

28 When restoring a standard backup, you must restore the logical logs by performing a logical restore. Physical and logical restores ON-Bar and ontape restore database serer data in two phases: The first phase is the physical restore, which restores data from backups of all or selected storage spaces. The second phase is the logical restore, which restores transactions from the logical-log backups. The database serer automatically knows which logical logs to restore. Physical restore During a physical restore, ON-Bar or ontape restores the data from the most recent leel-0, leel-1, and leel-2 backups. When you suffer a disk failure, you can restore to a new disk only those storage spaces with chunks that resided on the failed disk. The following figure illustrates a physical restore. Backup media Root dbspace Dbspace 1 Dbspace 2 Figure 1-5. Physical restore Logical restore As the following figure shows, the database serer replays the logical logs to reapply any database transactions that occurred after the last backup. The logical restore applies only to the physically restored storage spaces. Root dbspace Logical-log backup media Transactions INSERT... Dbspace 1 Dbspace 2 Figure 1-6. Logical restore For more information, see Chapter 6, Restore data with ON-Bar, on page 6-1 and Chapter 14, Restore with ontape, on page IBM Informix Backup and Restore Guide

29 Comparing ON-Bar and ontape IBM Informix proides two backup and restore utilities: ON-Bar Backs up and restores storage spaces (dbspaces) and logical files, by using a storage manager to track backups and storage media. Use this utility when you need to: Select specific storage spaces Back up to a specific point in time Perform separate physical and logical restores Back up and restore different storage spaces in parallel Use multiple tape dries concurrently for backups and restores Perform imported restores Perform external backups and restores ontape Logs, backs up, and restores data, and enables you to change the logging status of a database. It does not use a storage manager. Use this utility when you need to: Back up and restore data without a storage manager Back up without selecting storage spaces Change the logging mode for databases Restriction: The backup tapes that ontape and ON-Bar produce are not compatible. You cannot create a backup with ontape and restore it with ON-Bar, or ice ersa. The following table compares ON-Bar and ontape. If you are switching to ON-Bar and ISM from ontape, note that ON-Bar works differently. Table 1-1. Differences between ON-Bar and ontape Can the utility... ON-Bar ontape Use a storage manager to track backups and storage media? yes no Back up all database serer data? yes yes Back up selected storage spaces? yes no Back up logical-log files? yes yes Perform continuous logical-log backups? yes yes Perform continuous logical-log restore? yes yes Back up while the database serer is online? yes yes Back up while the database serer is in quiescent mode? yes yes Restore all database serer data? yes yes Restore selected storage spaces? yes yes Back up and restore storage spaces serially? yes yes Perform cold restores with the database serer offline? yes yes Initialize high aailability data replication? yes yes Restore data to a specific point in time? yes no Perform separate physical and logical restores? yes yes Chapter 1. Backup and restore concepts 1-7